chore: Add prettier to package directly

[rambleraptor]

We should have a pinned version of prettier and a task (npm run lint) to run/check the linter.

This ensures that we never have situations where the CI has different results than local runs.

[toumorokoshi]

Does this not lock it? https://github.com/aep-dev/aeps/blob/main/package.json#L5

an npm run sounds like a good idea (or maybe a more generic make lint so we can add it things like fix.py.